1. Field of the Invention
The invention involves a method for manufacturing golf clubs which are individually fitted to the user.
2. The Prior Art
Nowadays, golf clubs are fitted on demand according to the physical characteristics of a player, and, in fact not only in a static way, in which a test club is stood up on the floor and the shaft length as well as the angle between the clubhead and the shaft, the so-called lie angle, is measured according to the size of the golfer, but also in a dynamic way, by considering the swing action while hitting the golf ball. A golf club is said to be fitting if the sole of the clubhead touches the ground exactly in the middle at the moment of impact. If this is the case, the club neither turns to the right nor to the left, which would inevitably be the case with contact with the ground that is not in the middle.
Since a complete set includes 14 golf clubs, which all have different set angles for the face of the club (generally called “loft angle” or “loft” in short), it would theoretically be practical to manufacture all the golf clubs in the set in such a customized way that each club makes contact with the ground in the middle. However, it has been determined that it is considerably more important to adjust the short irons so that they fit exactly, while this does not seem to be so important for the long irons and the woods. Among the short irons are clubs such as the sand wedge (SW) with a loft of 55′ for instance, the pitching wedge with a loft of 48° for instance, the 9 iron with a loft of 44° for instance, and the 8 iron with a loft of 39° for instance. The so-called middle irons, the 7 to 5 irons, have a loft angle accordingly of 35° to 27° for instance, while the long irons, the 4 to 1 irons, can have a loft of 24° to 16° for instance.
It is now known that there are two methods of carrying out individual fitting. The static fitting method is the older of the two; it is generally called “static lie fitting” worldwide. The younger and thereby more modern dynamic method, which represents the state of the art today, is called “dynamic lie fitting.” With the latter method a golfer hits several golf balls for this purpose from a specially prepared surface, a so-called hitting board or “lie test hitting board.” This is a board that is approximately 1–3 cm thick, usually made of wood with the dimensions of 1 m×1 m. It should be measured so that a player can stand on the board and carry out the test shots. In order to provide the sole of the clubhead with a contact marking, a marked area is normally worked into the board, which shows a layer of color, for example graphite, and provides the sole of the clubhead with a colored marking for a shot that is made correctly, which represents the contact line of the sole with the hitting board.
Until now clubmakers have proceeded in such a way that if the contact line does not correspond with the middle of the sole, which is normally the case, then the angle between the shaft and the sole, which is called the “lie angle” (α), is altered by using a loft and lie machine to bend the angle, until the contact line is approximately congruent with the middle of the sole after repeated test shots.
A disadvantage of this “dynamic lie fitting method” is that not all golf clubs can be bent. In order to change the lie angle (α), the loft and lie machine must be applied to the head of the club and thereby change the angle between the head and the shaft neck, which, however, is only possible with forged clubs. Golf clubs that are cast cannot be bent because the material does not have the necessary elasticity and simply would break.
It is therefore the task of the invention to create an improved dynamic manufacturing method through which golf clubs, which are forged as well as cast or manufactured in another way, can be produced with an individual fit.
With this method practically all golf clubs can be manufactured with an optimal fit, regardless whether they are for men, women or children, and also in terms of the golfer's dynamic swing action. This is the case if the club length is properly fitted to the existing lie angle by taking into consideration the bending of the shaft at the moment of impact, the so-called “toe down bending,” so that the sole of the clubhead touches the ground exactly in the middle at the moment of impact and the clubhead does not twist at the moment of impact.
The stencil method makes previous fitting methods superfluous, i.e. changing the lie angle through bending while retaining the shaft length, because a set of clubs with the correct shaft length can now be manufactured for the user for the first time without changing the lie. Additionally the bending of the shaft during the shot is taken into consideration for the first time by analyzing the test shot with the help of a stencil. This bending apparently cannot be calculated, but only determined experimentally. The stencil method allows one to consider the bending that is experimentally determined through the test shot, which is marked on the sole of the clubhead; and the manufacturing of golf clubs that are fitted from the start.
In the first step the golf club manufacturer produces a group of test clubs with the same loft, however, with a different distance to the floor H (called “wrist-to-floor” (W-t-F)), for example the 9 iron (loft=44°; lie=64°) with W-t-F of 23″ to 38″, whereby the measurements are provided worldwide in inches [″] and independent of the usual system of measurement of Sl units in Europe [mm or cm]. Now it is not necessary to manufacture the test clubs in all sizes from 1″, for example 16 clubs for the 9 iron with the W-t-Fs of 23″, 24″ . . . 38″. It suffices if only those clubs are delivered, as they would approximately fit the customer waiting for the clubs, e.g. the 9 iron with W-f-Ts of 29″, 31″, 33″ and 35″.
It should be pointed out that it suffices if a golfers carries out the fitting based on a single test club, e.g. with a club type like the 9 iron with a distance to the floor (wrist-to-floor) that approximately fits, because if a club is correctly fitted then all the other clubs in the same set of clubs will fit, which also means the sand wedge (SW), the pitching wedge (PW), and the 8 to 1 irons.
In the second step a stencil is produced for a set of test clubs which indicates how far the contact point of the club sole is not aligned in the middle at the moment of impact with the ground, if one and the same person carries out a shot, for example, on a hitting board with golf clubs that have the same loft and lie angles, however, other wrist-to-floor distances.
In the third step the distance between the test person's wrist and the floor is measured in a vertical direction, which means the distance to the floor H (or wrist-to-floor (W-t-F)), and the best possible test club is selected.
In the fourth step the test person carries out a few shots on a hitting board with the test club that has already been chosen.
In the fifth step the club manufacturer takes the stencil that was produces according to the second step, holds it to the sole of the test club, and reads where the contact point, or the contact line, is located in terms of the middle of the sole.
In the sixth step the club manufacturer reads from the chart how long the club should be by taking into consideration the correction that was determined through the stencil and then cuts the shaft to the correct length.
In the seventh step only the grip has to be placed on the end of the shaft in the normal way.
The invention is explained below in detail based on the attached drawings.